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Boundary patterning
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Bank and ditch patterning
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Fall-off patterning

Fence and Gateway Patterning

Solid fences, such as stonewalls, will show a clear boundary between relatively high and low phosphate levels.  Fences that are not completely solid will show slightly more erratic, although still identifiable, increases in phosphate content.  Super-structural fences, such as horizontal wooden plank fences, and other boundary markers, such as lines of trees etc., are visible in this way.  Gateways can manifest similarly to entryways, as areas of low phosphate content that break linear bands of increased phosphate levels.  It is also possible for gateways to simply maintain the increase in phosphate content associated with the boundary function.  The specific phosphate level present along a physical boundary is greatly dependent on uses of the enclosed space and the surrounding area.  Enough organic material will collect along a physical boundary to be identifiable in the phosphate record even in areas where activities do not generate much organic debris as a result of low-level human activity.  


Pattern Maps and Interpretations

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Gateway patterning on the isthmus of the Dun Kilmore headland

Patterning denoting a constructed physical boundary is present in the phosphate results at the narrowest point of the neck on the Dun Kilmore headland, Achillbeg Island.  An increase in phosphate content spans the headland at this point, marking the meeting of the headland and the narrow isthmus.  This increase in phosphate content (Levels 3-4) suggests the presence of a gate structure, indicative of a constructed physical boundary in the area.  There is no visible feature on the ground surface associated with this patterning.  The pattern can indicate the presence of a bank, heave, wall or other structure directly to one side of the patterns to allow for the collection of organic material in its windfall. It is also possible that there was another structure present, of different composition than the visible features, on the isthmus nearer to the main body of the headland.  The possible gateway is located within the segregated space of the headland, interior to the bank and ditch complex.  The visible features are earthen with exposed stone cores; this phosphate increase could represent a wooden structure, thus accounting for the presence of a higher organic material content.  The presence of a gatehouse on the interior of the defendable complex fits well with these observations. Several examples of promontory forts with wooden or wicker gatehouses have been found upon excavation (Liversage 1968: 126; Greig 1971: 228).  It is likely that on Dun Kilmore any feature with a gatehouse function would have been a very simplified version, possibly no more than a small fence, thus accounting for the narrow band of increased phosphate values. 


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Irregular fence patterning associated with midden patterning at French Azilum

The presence of Level 5 concentrations in linear form suggests the collection of organic debris along a wall, or similar structure.   The boundary was probably more like a super-structural fence than a wall because there is no great decrease in phosphate content in the core of the patterning.   If this boundary did not manifest physically in the form of a wall or other feature, however, it would be visible as wider and less closely related shifts in phosphate concentration.  It is possible that this boundary was marked by the presence of a line of trees or other such segmented boundary.  The lack of a clearly defined midden in the yard area suggests that organic debris generated through use of the structure may have been deposited along the southern boundary rather than in a nucleated midden (see Midden patterning).

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Solid fieldwall patterning at French Azilum

This linear formation of relatively low phosphate content is associated with the presence of a modern fieldwall.  It is possible that the soils associated with anthropogenic phosphates in this area were removed during construction of the wall.  It is also possible, although less likely, that the modern wall follows the line of a pre-existing fieldwall that demarcated the limit of the yard area surrounding the slave quarters.

Johanna Ullrich, Ph.D.